Indian locomotive class WDM-7

The WDM-7 is a diesel-electric locomotive of Indian Railways. It has been manufactured by Banaras Locomotive Works (BLW), Varanasi. The model name stands for broad gauge (W), diesel (D), mixed traffic (M) engine. Today, these are found exclusively at Chennai Central and nearby area.

Indian locomotive class WDM-7
WDM-7 #11008 hauling a freight train; this loco is fuelled by bio-diesel
Type and origin
Power typediesel
BuilderBLW
ModelDL560C
Build date1987-1989
Total produced15
Specifications
Configuration:
​
 • UICCo′Co′
 • CommonwealthCo-Co
Gauge1,676 mm (5 ft 6 in)
BogiesALCO Asymmetric cast frame trimount
Wheel diameter1,092 mm (3 ft 7 in)
Wheelbase12.834 m (42 ft 1+1⁄4 in)
Length17.12 m (56 ft 2 in)
Width2.864 m (9 ft 4+3⁄4 in)
Height4.185 m (13 ft 8+3⁄4 in)
Axle load17,800 kg (39,200 lb)
Loco weight96,000 kg (212,000 lb)
Fuel typediesel
Fuel capacity5,000 L (1,100 imp gal; 1,300 US gal)
Prime moverALCO 251-B
RPM range400–1000 rpm
Engine typeV12 diesel
Traction motorsBHEL 4906 BZ and 4907 AZ
Cylinders12
Cylinder size228 mm × 266 mm (8.98 in × 10.47 in)
bore×stroke
TransmissionDiesel-electric transmission
MU working2 units[1]
Train brakesAir, Vacuum and Dual
Performance figures
Maximum speed105 km/h (65 mph)
Power outputMax:2,000 hp (1,500 kW)
Site rated:1,800 hp (1,300 kW)
Tractive effort25.3 t (25 long tons; 28 short tons)
Career
OperatorsIndian Railways
Numbers11001-11015
LocaleSR
Dispositionactive

These units have been retro-fitted with air brakes, in addition to the original vacuum brakes. The WDM-7 locos have a maximum speed of 105 km/h (65 mph),[2] restricted to 100 km/h (62 mph) when run long hood forward - the gear ratio is 94:17.

TNP WDM-7 resting in siding

History

Fifteen of these locomotives (road numbers #11001 to #11015) were built from 1987 to 1989 as a low-powered, “lightweight” version of the original ALCO. Like the WDM-6, maybe IR wanted a lower powered locomotive to handle small rake local and passenger services. However, all sheds declined them and they ended up at Ernakulam where they were used to handle local and shuttle services with good degrees of efficiency. Becoming aware of their abilities, SR moved all the WDM-7s out of Ernakulam to Tondiarpet, where they are housed today. These days, they are seen being used as shunters at Chennai Central or for light passenger haulage. One (#11008) has been modified to run on bio-diesel.

These Co-Co diesel-electric locomotives were designed primarily for branch-line duties (top speed 105 km/h). They have two 3-axle bogies. The power-pack is a 12-cylinder Alco 251B unit. They are a lower-powered variant of the WDM-2 (the latter produces 2600 hp of usable power, as opposed to the WDM-7 which produces 2000 hp). They were formerly housed at Erode and Golden Rock as well. They are reliable and rugged locomotives even though low-powered. They can be easily recognised by the lack of grilles on the short hood; in fact, they look exactly the same as the WDM-2 except for the “clean” short-hood-forward nose without grilles. Two locos currently operate on a mixture of bio-diesel and diesel. As of today, all 15 built are still in service.

Locomotive shed
ZoneNameShed CodeQuantity
Southern RailwayTondiarpetTNP14
Total Locomotives Active as of June 2023[3]14

Former

See also

References

Notes
  1. "WDM7_twins".
  2. Sheeju Chandran. "Interactive Diagram of the WDM-2 Locomotive". Indian Railways Fan Club.
  3. "IRFCA".

Bibliography
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